Biopharmaceutical filtration systems often utilize cassette filters for the ultrafiltration and diafiltration of macromolecules, such as monoclonal antibodies. Cassette filters, such as high mass transfer versions of Pellicon® 3 cassettes (EMD Millipore Corp., Billerica, Mass.), serve as the standard for desired system performance due to their compactness, high mass transfer rate, low cross flow requirements and acceptably low pressure drop. However, cassette filters must be run in compression holder assemblies, which typically consist of thick stainless steel holder plates and alignment rods. Compression is applied to the filters by tightening nuts or energizing hydraulic pistons. For single use applications, the cassettes are typically isolated from the expensive housing assemblies to prevent the housing assemblies from coming into contact with process fluids. Such isolation is achieved through the use of liner plates or plastic jackets encapsulating the cassettes. Both the housing assemblies and liner plates/plastic jackets are inconvenient to use and increase the cost and complexity of filtration systems.
Spiral-wound membrane modules are an attractive alternative to cassette filters because they obviate the need for compression holder assemblies. However, conventional spiral-wound membrane elements have much lower flux than cassette filters, and would require impractically large pumps or long filtration flow paths to achieve similar flux as cassette filters at the same cross flow rate, resulting in a system that is neither compact, nor easy to use. Accordingly, there is a need for efficient, compact, scalable and improved spiral-wound filter elements and elements that provide the performance advantages of cassette filters.